3Dconfocal Raman microscopy potentialities for the nondestructive confirmatory forensic identification of semen and postcoital fluid: sexual assault simulation

Abdel Razik, Heba Abdo; AbdelMaksoud, Sara Mohammed; Shokry, Dina Ali; Abdalsalam, Mervat HAMDY; Abd El Salam, Mohamed Ahmed; Basyoni, Hoda Ahmed

doi:10.21608/ejfsat.2025.390937.1378

3Dconfocal Raman microscopy potentialities for the nondestructive confirmatory forensic identification of semen and postcoital fluid: sexual assault simulation

Document Type : Original Article

Authors

¹ Forensic Medicine and Clinical Toxicology, Faculty of Medicine, Cairo University, Cairo 11562, Egypt

² Andrology, Sexology and STDs, Faculty of Medicine, Cairo University, Cairo 11562, Egypt.

³ department of forensic medicine and clinical toxicology, faculty of medicine, Cairo university

10.21608/ejfsat.2025.390937.1378

Abstract

Background: Violence against women is a global crisis, with 30% of women aged 15+ experiencing sexual or physical violence. Forensic identification of body fluids like semen and vaginal fluid is critical for sexual assault investigations, but current methods are often destructive, costly, or time-consuming. Raman spectroscopy offers a promising alternative due to its non-destructive nature and high specificity for trace analysis.
Aim of the Work: This study pioneers the use of Raman spectroscopy to characterize post-coital fluid (a natural mixture of semen and vaginal fluid) to simulate rape cases, while also evaluating spectral heterogeneity in semen from different donors.
Methodology: Post-coital vaginal swabs (15 samples) and semen samples (15 samples) were collected from volunteers, dried on glass slides, and analyzed using a WiTec alpha300 R confocal Raman spectrometer (532 nm laser, 50 mW power). Data were processed via OriginLab for peak identification and spectral comparison.
Results: Semen spectra exhibited distinctive peaks for choline (715 cm⁻¹), spermine phosphate (1065 cm⁻¹), and tyrosine (641, 1616 cm⁻¹). Post-coital fluid showed dominant urea/lactic acid peaks (577, 1445 cm⁻¹) with residual semen markers (715, 829 cm⁻¹), confirming mixed fluid detection. Donor variability in semen spectra was observed but did not obscure key biomarkers.
Conclusion: Raman spectroscopy reliably identifies post-coital fluid through unique spectral signatures, combining semen and vaginal fluid markers. This non-destructive method holds potential for on-site forensic applications in sexual assault cases. Further studies should explore environmental and substrate effects.

Keywords